PHYLUM CHORDATA

PHYLUM CHORDATA

                 - These are those animal which have notocord wheaher in larval , adult or through out life. in higher categories of animal these notochord change into vetebral column , which gives flexibility to the animal
- Their are about 1.2 million of animal species in this chordata

# Some Important characer of chordrates are :-

* Presence of Dorsal hollow nerve cord
* Pharyngeal gill slits
* Presence of tail, but it in human it reamin as assumption
- Largest class is insecta in this chordata which include about 750,000 animal species scattered on earth
- As we study evolution how organism modification occur we get some primitive type of chordates which are classified into mainly two

            i) Urochordates :-

              these are those chordates whose have notochord only at tail in larval state

Herdmania

                                                 

  ii) Cephalochordates :-

                 these are thiose animal whose have notochord which extent upto the head
these both have notochord by which they count in chordates , these animal also called non vertebrates , because their have notochord not vertebral column

@ Animal On The basis of Vertebral column :-

           - vertebrate are those animal which have vertebral column , these vertebral column are the modification of notochord in higher categories animal
- Vertebrates having further two sub division are :-

i) Aganthostomata :-

            these are those animal which are don't have jaw in their mouth , these are also called jaw less animal
     EX= Petromyzon ( Which include in class cyclostoma)

Petromyzon

ii) Gnathostoma :-

            * these are those animal which have jaw in their mouth ,
 * In Gnathostoma there are super class , which are based on locomotory organ are as :-

=> Pieces ( Super class) :-

          - these are those animal which found in water lake, pond , ocean etc . these are may be marine or fresh water
- But As we seen evolutionary point of view there are also stage of fish development , around where  u found a fish these may be of two type it may be Cartilagenous fish (Chondrichthyes) or may be Bony Fish (Osteichthyes)
- As their name suggest bony fish have bone which makes their skeleton ,where as cartilage fish made up of only cartilage tissue

=> Tetrapoda (Super class) :-

Tetrapoda

            * These are those animal which have four limbs for locomotion
* In animal kingdom there are four type of tetrapoda found on the basis of skin they are differentiated are as :-

i) Amphibia ;-

       - these are those animal which live both land and water
- these animal have developed lungs to respire in fresh air
- Ex like turtle, crocodile they are oviparous , they lay egg
- Most important character is that their skin thin and moist

ii) Reptilia :-

         - these are those animal show great difference other
- Some animal in this show camouflage (set their colour according to climate)
- Ex like charmeleon
- Most important character is those are that their skin covered by epidermal scales

iii) Aves :-

       * By evolutionary point of view these are those animal whose developed wings , and can fly in air
* For flying these animal have light weight, hollow bone, and wings in place of weather
* Ex = Parrot, pigeon etc
* These animal covered with feather

iv) Mammalian :-

         - these are those animal whose have mammary gland for feeding their young one
- In this animal development of baby is internal
- Most important character of this mammal are have ear pinna in external ear , but in case of whale these assumption taken by tympanic membrane and mammary gland
- These animal are most modified animal in origin
- Their Skin covered with hair